Electrodeposition of nickel



2,731,305 ELECTRoD'EPosrrIbN or NICKEL Henry Brown, Huntington Woods, assignor to The Udylit Research Corporation, Detroit, Mich.-, a corporation of Michigan N6 Drawing. Ap lication August '14, iss', sens! N6. 374,418

14 Claims. (Cl. 204 49) This invention relates to the elect-rodepbsition of nickel from an aqueous acidic bath. U

One object of this invention is to decrease the grain size and increase the luster of the nickel deposit, M

A second and major object is the electrodeposition of brilliant, highly lustrous, ductile nickel plate.

It has been found that these objects can be accomplished by the use of certain organic compounds in the aqueous acidic nickel baths. U

The first object mentioned above can be accomplished by the addition to the Watts type of nickel bath or its modifications of certain amides carrying an unsaturated olefinic group. The presence of these particular amides, which are more specifically illustrated by the compounds set forth in Table HI, may be designated generally by Formula A.

FORMULA A where R1 and R2 are selected from the group consisting of hydrogen, acetyl, chlorine, bromine, methyl, methyl carb'oxy, carbonyl, carboxy and aldehyde, phenyl and furyl and the chloro, bromo, acetyhmjethyl, carboxy, amino, methoXy, ethoxy, dioxymethylene, carbonyl amido, hydroxy and ethyl substitution products of phenyl and furyl, R3 and R4 are selected from the group consisting of hydro-gen, methyl, formyl, acetyl, amino, amido, imido, carboxy, carbonyl, benz' 'oyl and nicotinoyl radieals; The types of compounds which are encompassed by Foi' inula A are illustrated in the compounds designated A, B, C and D.

COMPOUND A When R1, R2, R3 and R4 are hydrogen, we have om=oH-i i-'NH2 Acrylamide COMPOUND B When R1 is a phenyl, R2, R3 and R4 are hydrogen, we: have H H 11 C OC'-NHz Cinnami amide CoMP'oUNn C When R1 is methyl carboxy, R2, R3 and'Rs are hydrogen, we have 110- o-o CH3 HCfi-NH1 V Monomethyl malic acid moiioa nide (methyl ester of v I maleamic acid) "ice 3 V COMPOUND D When is carbonyl, R2 and Rs are chlorine and R4 is hydrogen, we have 11 010- 041 CIC-fi-NH:

compounds represented by Formula A, of a material con- I i fillllg another and diflerent functional group, namely, the unsaturated methylene sulfone group, =C SO2, as :"eX mplified by benzene sulfonamides and, sulfoniinides. 1e presence of a compound represented by Formula A none in a Wattstype nickel bath, or thepiesenceof a material containing the unsaturated methylene sulfone group alone, gives no obvious indicationof the remarkably different and enhanced result which occurs when both marshals "nenrreafly present. p

While the simpler aryl sulfdnar'nides andsoineof the aryl sn a as preaueebngtit and mirror like deposits I fals such as buffed brass, these compounds fail to aecoinplish the same result: onsteel which is polished, for example, with 200 emery paper orwhere the nickel i's plated on top of matte (but unburnt) copper plate of 0.003" to 0.0005" thickness, and yield in these cases plate of dull and grey appearance. If, however, the compound represented by Formula A and a material containing the unsaturated methylene sulfone group are used together, a brilliant mirror-lil-ge deposit can be obtained even on a inane copper deposit. I

The aryl sulfones (s'ulfenamides, sulfonic acids) in general do not have a critical concentration range in the bath, and they produce practically no further improvernent after their optimum concentration is attained. In the case of a compound represented by Formula A, it is thought that a-mechani'sm of the functioning in a Watts type nickel bath comprises a preferential reduction of the unsaturated compound with respect to 'the nickel ion, whereas with the aryl sulfones, the nickel ion is reduced preferentially; The variation of the reduction with the variation of the potentials between adjacent high and low points will account for the rate of brightening, or smoothning out efiect.

The uniqueness of the aryl sulfones, or broadly the compounds, seems to be mainly tied up' with the rate of reduction of the positive valent sulfur compound to negative valent sulfur compound, and the mechanism of its deposition. The fact that with u-naphthalene sulfonamide as the only organic compound in the bath, not only is the odor of naphthalene apparent at the cathode during the plating, but also the analysis of the plate shows the presence of carbon as well as sulfur, and this indicates that the mechanism of the reduction is not of the simplest form.

It is not the sulfone group alone that is responsible forthe efiect of the aryl sulfones because the saturated alkyl sulfones are not nearly as efiective as the aryl sulfones, The benzene and toluene sulfonamides and ortho benzoyl sulfonimide are more effective than aryl monosulfonic acids, especially of the benzene series,

nevertheless, the latter, even though they may not produce bright plate on bufi'ed metals, will give brilliant ductile plate when used in combination with a compound represented by Formula A.

The concentration of a compound represented by Formula A or a mixture thereof which may be advantageously employed is not critical in any concentration up to saturation, and may be used at concentrations between about 0.1 to about 2.0 grams/liter, the preferred concentration being .6-1.2 grams/liter.

In keeping with their chemical activity, the higher the temperature of the bath, the more active are the unsaturated groups in the bath and smaller concentrations of compounds carrying them must be used. Furthermore, they function best at the higher pH values of the nickel bath, that is, 3.0 to 5.2, and their effectiveness in most cases drops rather suddenly when the pH is lowered past a certain value (in general, at a pH below 3.0 or 2.5, depending on the type of unsaturated compound and on the temperature). The lower the temperature, the higher are the pH values that should be used, and conversely.

The best cathode film bufier is boric acid and it is important to keep its concentration high (over 30 grams/liter), especially in the warm baths. Other buffers may be used in small amount (1 to grams/liter) with the boric acid with beneficial efiects, such as formic,

citric, fluoboric acids, etc., but they are not recommended to be used alone.

11. 7-aldehydo o-benzoyl sulfimide 0.1-3 l2. N-acetyl benzene sulfonimide 0.1-2 13. Methoxy benzene sulfonamides 0.1-1 14. Hydroxymethyl benzene sulfonamide 0.1-2 15. Vinyl sulfonamide 4-12 16. Allyl sulfonamide 4-12 17. Benzene sulfonic acids (mono-, di, and

tri-) 1-15 18. p-Brom benzene sulfonic acid 3-6 19. Benzaldehyde sulfonic acids (0, m, p)- 2-6 20. Diphenyl sulfone sulfonic acid 1-8 21. Naphthalene sulfonic acids (monodi-,

and tri-) 1 1-8 22. Benzene sulfohydroxamic acid 1-5 23. p-Chlor benzene sulfonic acid 1-15 24. Diphenyl sulfonic acid 1-5 25. m-Diphenyl benzene sulfonic acid 1-4 26. 2-chloro-5-sulfobenzaldehyde 1-5 27. m-Benzene disulfonamide 0.5-1 28. Allyl sulfonic acid 4-12 29. Cinnamyl sulfonic acid 0.1-8 30. Cinnamyl sulfonamide 0.1-3

In Table HI are listed representative examples of specific compounds which are covered by Formula A and are suitable for the purposes of this invention, when used alone in a Watts type nickel bath or in combination with organic sulfonamides, sultonimides and sulfonic acids of Table II.

In the use of a compound represented by Formula A alone in the bath, or in the presence of the aryl sulfones, ammonium salts should be kept at a minimum. A con- Table centration of zinc and copper ions in the bath should also be kept as low as possible. This is especially desirable Optimum where the concentration of aryl sulfones are low in the Oom- Unsaturated amides 00110., bath or the latter compounds are absent. 3,? i t? The baths may be operated at pH values ranging from 2.0 to 5.5 and temperatures rang ng from 20 C. to 70 Acrylamide C., and the preferred current density ranges may be from 5 to 150 amps/sq. ft., depending on the agitation, the 815:5 temperature of the bath and the concentration and the fioac y n de--- type of nickel salts. The benzene sulfonamides and sulgl fifiggggfgggggiagj 11111: 8131i fommides may be used effectively in concentrations of Methacrylflmlde from 0.05 gram/liter to saturation. 31333 In Table I are listed preferred bath compositions. 8-H 2 Table 1 3&

0.1-1. 0.1-1 NISO Nion. B31308, N1(BF4);, Temp. Optimum 0.1-1: LEE/I120, 2 l gl PH N-nlcotluoyl acrylamide 0. g N-allylacrylamlde 0.1-1. 0a- -me Y acrya 3 5 8 g N-benzoyl acrylamide 0. 1-1. 75-100 200-250 35-40 -05 2'. HI 5 fifggififiififig ag m 200-250 30-00 35-40 7-15 40-50 2. s-5. 0 Mucobmmic i amide" 011-11 O40 15O30O 40-50 0 N-tert, buty13ery1amide 0. 1-1. N-acrylourea 0. 1-1. fi-Piperonylacrylamide 0. 1-1. In Table II are listed representative examples of or- 8 gzgnc sulfonamides, sulfonimides and sulfonic acids 31- p-caiigonsg-amlide cinnarlraic) amide (p-oarbon l- 1 2 am 6 en acryam e w lch may be employed 1n con unctlon wlth the add1t1on 32 Acetyl%mmm amide 0.141 itlglents represented by Formula A and typified in Table as Mono Z-methoxyethylmalelo acid monoamlde 0.1-1.2

Table II Optimum cone.

Although Table HI shows the optimum concentration of the compounds therein listed to be between 0.1 and 1.2 grams/liter, these compounds may be used in concentrations up to saturation, especially when used in conjunction with benzene sulfonamides, toluene sulfonamides and o-benzoyl sulfimide. In general, a concentration higher than about 2.5 grams per liter is unnecessary.

It will be understood that any of the compounds listed in Table III may be used separately in a Watts type nickel bath or in combination with any of the organic sulfonamides, sulfonimides or sulfonic acids of Table II in any of the typical baths set forth in Table I. For purposes of further illustration, the examples given below set forth certain preferred embodiments of the invention.

NNKDNNNNNNNNNNNNNNNN EXAMPLE I Grams/liter NiSO4.6H2O antennas- ..-ss; 250-300 NiQlz.6IhO 60 Hanoi 4s Acrylamide I v v 1.0-1.8 Benzene sulfona 'de 0.5-3

EXAMPLE II Grams/liter NiSO4.6HzO 250-300 NiClz.6H2O 40-60 H3BO3 40-50 Cinnamic amide 0.6-1.2 Benzene sulfonamide 0.5-3

EXAMPLE III Grams/liter NiSO4.6H2O 50 NiClz.6I-I2O 250 HsBOs 40-50 Z-furanacrylamide 0.8 o-Benzoyl sulfimide 1-2 0- or p-Toluene sulfonamide 13 EXAMPLE IV Grams/liter Ni(BF4)2 100-200 HsBOs 3O Fumaramide 1 0.81.5 o-Benzoyl sulfimide 1-2 1 (Sat) The addition agents of this invention may consist of a compound or mixture of compounds represented by Formula A as such, or may consist of an admixture of at least one compound represented by Formula A and at least one compound selected from the group consisting of organic sulfonamides, sulfonimides and sulfonic acids.

This application is a continuation-in-part of my prior application, Serial No. 749,344, filed May 20, 1947, which was itself a continuation-in-part of my prior application, Serial No. 366,385, filed November 20, 1940, both of which are now abandoned.

What is claimed is:

1. A bath for electrodepositing fine-grained lustrous nickel comprising an aqueous acidic nickel solution consisting essentially of at least one material selected from the group consisting of nickel sulfate, nickel chloride and nickel fiuoborate, having dissolved therein at least one brightener selected from the group consisting of organic sulfonamides, sulfonimides and sulfonic acids, and additionally a minor amount of a compound having the formula r at r where R1 and R2 are selected from the group consisting of hydrogen, chlorine, bromine, methyl, methyl carboxy, carbonyl, carboxy, aldehyde, phenyl, furyl and the chloro, bromo, acetyl, methyl, carboxy, amino, methoxy, ethoxy, dioxymethylene, carbonyl amido, hydroxy and ethyl substitution products of phenyl and furyl, R3 and R4 are selected from the group consisting of hydrogen, methyl, formyl, acetyl, amino, amido, imido, carboxy, carbonyl, benzoyl and nicotinoyl radicals.

2. A bath for electrodepositing bright nickel comprising an aqueous acidic nickel solution consisting essentially of at least one nickel salt selected from the group consisting of nickel sulfate, nickel chloride and nickel fluoborate, having dissolved therein about 0.1 gram per liter to saturation of at least one brightener selected from the group consisting of organic sulfonamides, sulfonimides, and sulfonic acids, and about 0.1 gram per liter to saturation of a compound having the formula whereRr and Rz-are selected from the group consisting of hydrogen, chlorine, bromine, methyl, methyl carboxy, carbonyl, carboxy, aldehydo, phenyl, furyl and the chloro, bromo, acetyl, methyl, carboxy, amino, methoxy, ethoxy, dioxymethylene, carbonyl amido, hydro xy and ethyl substitution products of phenyl and furyl, R3 and R4 are selected from the group consisting of hydrogen, methyl, formyl, acetyl, amino, amido, imido, carboxy, carbonyl, benzoyl and, nicotinoyl radicals.

3. A method for electrodepositing nickel to obtain bright nickel comprising the step of electrodepositing nickel from an aqueous acidic nickel solution consisting essentially of at least one material selected from the group consisting of nickel sulfate, nickel chloride and nickel fluoborate, in the presence of at least one brightener selected from the group consisting of organic sulfonamides, sulfonimides and sulfonic acids and additionally a minor amount of a compound soluble in the said acid nickel solution having the formula where R1 and R2 are selected from the group consisting of hydrogen, chlorine, bromine, methyl, methyl carboxy, carbonyl, carboxy, aldehydo, phenyl, furyl and the chloro, bromo, acetyl, methyl, carboxy, amino, methoxy, ethoxy, dioxymethylene, carbonyl amido, hydroxy and ethyl substitution products of phenyl and furyl, R3 and R4 are selected from the group consisting of hydrogen, methyl, formyl, acetyl, amino, amide, imido, carboxy, carbonyl, benzoyl and nicotinoyl radicals.

4. A method for electrodepositing nickel to obtain bright nickel comprising the step of electrodepositing nickel from an aqueous acidic nickel solution consisting essentially of at least one material selected from the group consisting of nickel sulfate, nickel chloride and nickel fiuoborate, in the presence of about 0.1 gram per liter to saturation of at least one brightener selected from the group consisting of organic sulfonamides, sulfonimides and sulfonic acids, and about 0.1 gram per liter to saturation of at least one compound soluble in the said acid nickel solution having the formula Where R1 and R2 are selected from the group consisting of hydrogen, chlorine, bromine, methyl, methyl carboxy, carbonyl, carboxy, aldehyde, phenyl, furyl and the chloro, bromo, acetyl, methyl, carboxy, amino, methoxy, ethoxy, dioxyrnethylene, carbonyl amido, hydroxy and ethyl substitution products of phenyl and furyl, R3 and R4 are se' lected from the group consisting of hydrogen, methyl, formyl, acetyl, amino, amido, imido, carboxy, carbonyl, benzoyl and nicotinoyl radicals.

5. A bath in accordance with claim 1 wherein the unsaturated amide is cinnamic amide and is present in an amount of about 0.1 to 1.2 grams/ liter.

6. A bath in accordance with claim 1 wherein said unsaturated amide is o-chlorocinnamic amide and is present in an amount of about 0.1 to 1.2 grams/liter.

7. A bath in accordance with claim 1 wherein said unsaturated amide is mucochloric acid amide and is present in an amount of about 0.1 to 1.2 grams per liter.

8. A bath in accordance with claim 1 wherein said unsaturated amide is acrylamide and is present in an amount of about 0.1 to 1.2 grams/ liter.

9. A bath in accordance With claim 1 wherein said unsaturated amide is N-methyl acrylamide and is present in an amount of about 0.1 to 1.2 grams/liter.

10. A method in accordance with claim 3 wherein said unsaturated amide is cinnamic amide and is present in an amount of about 0.1 to 1.2 grams/liter.

11. A method in accordance with claim 3 wherein said unsaturated amide is o-chlorocinnamic amide and is present in an amount of about 0.1 to 1.2 grams/liter.

12. A method in accordance with claim 3 wherein said unsaturated amide is mucochloric acid amide and is present in an amount of about 0.1 to 1.2 grams/liter.

13. A method in accordance with claim 3 wherein said unsaturated amide is acrylamide and is present in an amount of about 0.1 to 1.2 grams/liter.

14. A method in accordance with claim 3 wherein said unsaturated amide is N-methyl acrylamide and is present in an amount of about 0.1 to 1.2 grams/ liter.

References Cited in the file of this patent UNITED STATES PATENTS Donnelly Aug. 11, 1953 OTHER REFERENCES 7 Raub et a1.: Metal Finishing, June 1940, pp. 315-316. 

1. A BATH FOR ELECTRODEPOSITING FINE-GRAINED LUSTROUS NICKEL COMPRISING AN AQUEOUS ACIDIC NICKEL SOLUTION CONSISTING ESSENTIALLY OF AT LEAST ONE MATERIAL SELECTED FROM THE GROUP CONSISTING OF NICKEL SULFATE, NICKEL CHLORIDE AND NICKEL FLUOBORATE, HAVING DISSOLVED THEREIN AT LEAST ONE BRIGHTENER SELECTED FROM THE GROUP CONSISTING OF ORGANIC SULFONAMIDES, SULFONIMIDES AND SULFONIC ACIDS, AND ADDITIONALLY A MINOR AMOUNT OF A COMPOUND HAVING THE FORMULA 